PSA: One Question, Many Answers

Action Points

The importance of PSA testing to men varied according to the strategy used to identify factors that might influence the decision-making process, a study found.

Point out that more than half of men valued reducing the odds of prostate cancer death as their priority when asked to rate or rank factors by importance.

The importance of PSA testing to men varied according to the strategy used to identify factors that might influence the decision-making process, a study of values clarification found.

More than half of men valued reducing the odds of prostate cancer death as their priority when asked to rate or rank factors by importance, according to Michael Patrick Pignone, MD, of the University of North Carolina at Chapel Hill, and colleagues. In contrast, about a third of men considered the risk of prostate cancer death as their priority when presented with a balance sheet of potential benefits and harms, or when asked to choose between hypothetical outcomes associated with PSA screening.

Similar variation appeared in responses to other values-clarification exercises, although about three-fourths of the men said they intended to undergo PSA testing, irrespective of their responses, they reported online in JAMA Internal Medicine.

"Different values clarification methods produce different patterns of attribute importance and different preferences for screening when presented with an unlabeled choice," the authors wrote. "Further studies with more distal outcome measures are needed to determine the best method of values clarification, if any, for decisions such as whether to undergo screening with PSA."

A man's decision to undergo PSA testing involves a complex interaction of beliefs, values, and information. High-quality decision processes should inform patients and incorporate their values, the researchers noted in their introduction.

Decision aids can provide patients with information useful for making preference-sensitive decisions. The aids have been shown to improve patient knowledge, reduce uncertainty, and encourage shared decision-making, the authors continued.

Few studies have evaluated the decision aids with explicit values clarification versus those without, or compared different values clarification techniques. To address the lack of information, Pignone and colleagues conducted a randomized trial to compare one implicit method of values clarification and two techniques that involve explicit values clarification methods.

Investigators in the U.S. and Australia recruited men from an online survey panel. Each participant completed a baseline questionnaire and reviewed basic information about PSA testing and associated decision making. The men were randomized to one of the three values clarification techniques and completed a values clarification task. Finally, the participants completed a posttest questionnaire.

Investigators described PSA decision options in terms of four key attributes: the risk of dying of prostate cancer, the risk of biopsy, the risk of a prostate cancer diagnosis, and the risk of becoming impotent or incontinent as a consequence of treatment.

The three values clarification techniques were:

Balance sheet: Involved implicit values clarification and was based on modeling studies of PSA-related outcomes, randomized clinical trials, and observational evidence. Men allocated to this group chose the most important of the four key attributes.

Rating and ranking: Participants assigned a value of 0 to 5 to a list of attributes associated with PSA testing, and they were asked to rank the three most important attributes from sets of the key attributes.

Discrete choice experiment: Participants chose between hypothetical alternatives defined by four key attributes. As an example, participants chose an acceptable 10-year risk for diagnosis of prostate cancer: 60 in 1,000 or 40 in 1,000.

The primary outcome was the highest-valued attribute determined by patients. The final analysis included 911 survey panel participants.

The results showed that 54% of men assigned to rating and ranking chose the likelihood of dying of prostate cancer as the most important attribute, compared with 35.1% of the balance-sheet group, and 32.5% of the men assigned to discrete choice experiment (P<0.001).

A higher proportion of the balance-sheet group (43.7%) preferred a PSA-like screening option over an option similar to no screening, as compared with 34.2% of the rating and ranking group and 20.2% of the discrete choice experiment group.

The balance-sheet group assigned almost equal importance to the risk of prostate cancer death and the risk of prostate cancer diagnosis (35.8%). The diagnosis risk was second in importance for the other two groups. The chance of developing treatment-induced incontinence or impotence was the third most important attribute in all three groups, and the risk of biopsy was the least important of the key attributes across all three study groups.

"The conceptualization of preferences measurement as values clarification has important implications for outcomes," Sara J. Knight, PhD, of the Department of Veterans Affairs, said in an accompanying editorial.

"If the measurement itself is likely to change the preferences, as might be the case in values clarification, the preferences expressed in the initial scores on the measures may represent a preliminary value and not the value that is revealed through the values clarification process."

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